Mirror drive device capable of high-speed driving and image pickup apparatus

ABSTRACT

A mirror drive device capable of achieving lower torque and higher speed in mirror driving without necessitating reversing of an urging direction of an urging member during the mirror driving and improve durability thereof at the same time. A main mirror holder holding a main mirror is movable between a mirror-down position is a photographing optical path and a mirror-up position retracted from the photographing optical path. A sub mirror holder holding a sub mirror and rotatably attached to the main mirror bolder is movable between a mirror-down position and a mirror-up position. The sub mirror holder is moved by a driving member from the mirror-down position to the mirror-up position, whereby the main mirror holder is moved from the mirror-down position to the mirror-up position.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a mirror drive device equipped with a mechanism for high-speed driving of a mirror unit provided in an image pickup apparatus, such as a single-lens reflex camera, and an image pickup apparatus equipped with the mirror drive device.

Description of the Related Art

In a quick return mirror mechanism e.g. of a single-lens reflex camera, a mirror unit provided with a main mirror and a sub mirror is moved at high speed between a mirror-down position in which the mirror unit enters a photographing optical path and a mirror-up position in which the mirror unit is retracted from the photographing optical path. Each of the mirrors of the mirror unit is brought into contact with a stopper formed in a mirror box, at the mirror-down position, thereby being held in a predetermined stop position, to guide an object light flux having passed through a photographic optical system of the lens unit to a viewfinder optical system and a focus detection unit.

Conventionally, there has been proposed a mirror drive device that drives the mirror unit between the mirror-down position and the mirror-up position by transmitting a driving force to the main mirror of the mirror unit and causing the sub mirror to follow the main mirror using a toggle spring and a reversing cam. In the proposed mirror drive device, the toggle spring urges the sub mirror in a mirror-down direction when the mirror unit is in the mirror-down position, and urges the same in a mirror-up direction when the mirror unit is in the mirror-up position (see Japanese Patent Laid-Open Publication No. 2011-85762).

According to the mirror drive device proposed in Japanese Patent Laid-Open Publication No. 2011-85762, in order to achieve high turning speed of the mirror unit, it is required to increase the spring force of the toggle spring for urging the sub mirror. However, if the spring force of the toggle spring is increased, the mirror unit reaches the mirror-down position or the mirror-up position at the increased turning speed of the sub mirror and the main mirror, which causes a large bounce of each mirror and an increase in mirror driving sound.

Further, according to the mirror drive device proposed in Japanese Patent Laid-Open Publication No. 2011-85762, a large torque is required for reversing the urging direction of the toggle spring for urging the sub mirror following the main mirror between the mirror-up position and the mirror-down position. For this reason, there is a limit to increasing mirror driving speed. Further, a large load is applied to the reversing cam that reverses the direction of urging the sub mirror, and hence there is concern about the durability of the mirror drive device.

SUMMARY OF THE INVENTION

The present invention provides a mirror drive device and an image pickup apparatus which make it possible to achieve lowered torque and increased speed in mirror driving without requiring reversing of the urging direction of an urging member during the mirror driving, and improve the durability of the mirror drive device at the same time.

Further, the invention provides a mirror drive device and an image pickup apparatus which are capable of not only driving a mirror at high speed, but also reducing the magnitude of mirror bounce or mirror driving sound during the mirror driving.

In a first aspect of the invention, there is provided a mirror drive device comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatably attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, and a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, wherein the driving member moves the second mirror holder from the third position to the fourth position, whereby the first mirror holder is moved from the first position to the second position.

In a second aspect of the invention, there is provided a mirror drive device comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatably attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, and a control unit configured to control driving of the motor, wherein when the second mirror holder is moved from the third position to the fourth position by the driving member, the first mirror holder is positioned in the first position without being moved until the second mirror holder is brought into contact therewith, and after the second mirror holder is brought into contact therewith, the first mirror holder is moved to the second position together with the second mirror holder, and wherein the control unit controls the motor to reduce speed thereof to thereby reduce speed of the second mirror holder when the second mirror holder reaches a predetermined first setting position before the second mirror holder is brought into contact with the first mirror holder, controls the motor to increase the speed thereof to thereby increase the speed of the second mirror holder after the second mirror holder is brought into contact with the first mirror holder, and controls the motor to reduce the speed thereof to thereby reduce the speed of the second mirror holder when the first mirror holder is moved toward the second position together with the second mirror holder and reaches a predetermined second setting position advance before reaching the second position.

In a third aspect of the invention, there is provided a mirror drive device comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatable attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, and a control unit configured to control driving of the motor, wherein when the second mirror holder is moved from the fourth position to the third position by the driving member, the first mirror holder is moved from the second position toward the first position together with the second mirror holder, and reaches the first position, and after the first mirror holder reaches the first position, the second mirror holder is moved toward the third position, and reaches the third position, and wherein the control unit controls the motor to reduce speed thereof to thereby reduce the speed of the second mirror holder when the first mirror holder is moved from the second position toward the first position together with the second mirror holder and reaches a predetermined first setting position before reaching the first position, controls the motor to increase the speed thereof to thereby increase the speed of the second mirror holder after the first mirror holder reaches the first position, and controls the motor to reduce the speed thereof to thereby reduce the speed of the second mirror holder when the second mirror holder reaches a predetermined second setting position before reaching the third position.

In a fourth aspect of the invention, there is provided an image pickup apparatus comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatably attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, and a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, wherein the driving member moves the second mirror holder from the third position to the fourth position, whereby the first mirror holder is moved from the first position to the second position.

In a fifth aspect of the invention, there is provided an image pickup apparatus comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatably attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, and a control unit configured to control driving of the motor, wherein when the second mirror holder is moved from the third position to the fourth position by the driving member, the first mirror holder is positioned in the first position without being moved until the second mirror holder is brought into contact therewith, and after the second mirror holder is brought into contact therewith, the first mirror holder is moved to the second position together with the second mirror holder, and wherein the control unit controls the motor to reduce speed thereof to thereby reduce speed of the second mirror holder when the second mirror holder reaches a predetermined first setting position before the second mirror holder is brought into contact with the first mirror holder, controls the motor to increase the speed thereof to thereby increase the speed of the second mirror holder after the second mirror holder is brought into contact with the first mirror holder, and controls the motor to reduce the speed thereof to thereby reduce the speed of the second mirror holder when the first mirror holder is moved toward the second position together with the second mirror holder and reaches a predetermined second setting position before reaching the second position.

In a sixth aspect of the invention, there is provided an image pickup apparatus comprising a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path, a second mirror holder that holds a second mirror in a state rotatably attached to the first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, a motor, a driving member configured to be driven by the motor to thereby move the second mirror holder between the third position and the fourth position, and a control unit configured to control driving of the motor, wherein when the second mirror holder is moved from the fourth position to the third position by the driving member, the first mirror holder is moved from the second position toward the first position together with the second mirror holder, and reaches the first position, and after the first mirror holder reaches the first position, the second mirror holder is moved toward the third position, and reaches the third position, and wherein the control unit controls the motor to reduce speed thereof to thereby reduce the speed of the second mirror holder when the first mirror holder is moved from the second position toward the first position together with the second mirror holder and reaches a predetermined first setting position before reaching the first position, controls the motor to increase the speed thereof to thereby increase the speed of the second mirror holder after the first mirror holder reaches the first position, and controls the motor to reduce the speed thereof to thereby reduce the speed of the second mirror holder when the second mirror holder reaches a predetermined second setting position before reaching the third position.

According to the first and fourth aspects of the invention, it is possible to provide a mirror drive device and an image pickup apparatus which make it possible to achieve lowered torque and increased speed in mirror driving without requiring reversing of the urging direction of the urging member during the mirror driving and improve durability thereof at the same time.

According to the second, third, fifth and sixth aspects of the invention, it is possible to provide a mirror drive device and an image pickup apparatus which are capable of not only driving a mirror at high speed, but also reducing the magnitude of bounce of the mirror or mirror driving sound during the mirror driving.

Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the system configuration of a digital single-lens reflex camera which is an image pickup apparatus equipped with a mirror drive device according to an embodiment of the present invention.

FIG. 2A is a schematic side cross-sectional view of the digital single-lens reflex camera in a mirror-down position.

FIG. 2B is a schematic side cross-sectional view of the digital single-lens reflex camera in a mirror-up position.

FIG. 3 is an exploded perspective view of a mirror drive unit.

FIG. 4 is an exploded perspective view of a mirror charge unit.

FIG. 5A is a front view of the mirror drive unit as viewed from an optical axis direction.

FIG. 5B is a right side view of the mirror drive unit shown in FIG. 5A.

FIG. 6 is a view of the mirror drive unit shown in FIG. 5B, with its motor and gear base removed therefrom.

FIG. 7 is a view useful in explaining the relationship between a mirror unit and the mirror charge unit.

FIGS. 8A to BE are views useful in explaining states of components of the mirror drive unit when the mirror unit is in the mirror-down position.

FIGS. 9A to 9E are views useful in explaining states of the components of the mirror drive unit immediately before a cam gear and a mirror drive gear are brought into mesh with each other immediately after the mirror drive unit starts mirror-up driving.

FIGS. 10A to 10E are views useful in explaining states of the components of the mirror drive unit immediately before the mirror unit starts a mirror-up operation.

FIGS. 11A to 11E are views useful in explaining states of the components of the mirror drive unit when a sub mirror holder is performing its mirror-up operation.

FIGS. 12A to 12E are views useful in explaining states of the components of the mirror drive unit when a main mirror holder starts its mirror-up operation.

FIGS. 13A to 13E are views useful in explaining states of the components of the mirror drive unit immediately before the mirror unit completes the mirror-up operation.

FIGS. 14A to 14E are views useful in explaining states of the components of the mirror drive unit when the mirror unit is in the mirror-up position.

FIGS. 15A to 15E are views useful in explaining states of the components of the mirror drive unit immediately after the mirror drive unit starts mirror-down driving.

FIGS. 16A to 16E are views useful in explaining states of the components of the mirror drive unit immediately before the mirror unit starts a mirror-down operation.

FIGS. 17A to 17E are views useful in explaining states of the components of the mirror drive unit when the main mirror holder reaches its mirror-down position.

FIGS. 18A to 18E are views useful in explaining states of the components of the mirror drive unit immediately before the sub mirror holder reaches its mirror-down position.

FIG. 19A is a graph showing the relationship between the position of the mirror unit and time during the mirror-up operation.

FIG. 19B is a graph showing the relationship between the position of the mirror unit and time during the mirror-down operation.

FIG. 20A is a flowchart of a mirror drive control process performed during the mirror-up operation of the mirror unit.

FIG. 20B is a flowchart of a mirror drive control process performed during the mirror-down operation of the mirror unit.

DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail below with reference to the accompanying drawings showing embodiments thereof.

FIG. 1 is a block diagram of the system configuration of a digital single-lens reflex camera which is an image pickup apparatus equipped with a mirror drive device according to an embodiment of the present invention.

Referring to FIG. 1, in the digital single-lens reflex camera (hereinafter referred to as the camera) according to the present embodiment, an interchangeable lens unit 210 is mounted on a camera body 1 via a mount contact portion 21 in a removable manner.

First, a description will be given of the camera body 1. In FIG. 1, a microcomputer 100 (hereinafter referred to as the MPU 100) controls the overall operation of the camera. An EEPROM 100 a incorporated in the MPG 100 stores time information of a time measurement circuit 109, control programs, and other information items. To the MPU 100, there are connected a mirror drive circuit 101, a focus detection circuit 102, a shutter drive circuit 103, a video signal processing circuit 104, a switch sensing circuit 105, and a photometric circuit 24 of a viewfinder optical system 4. Further, to the MPU 100, there are connected a display drive circuit 107, a battery check circuit 108, the time measurement circuit 109, a power supply circuit 110, and a piezoelectric element drive circuit 111, and these circuits are driven by the control of the MPU 100.

A mirror unit 500 includes a main mirror 501 formed by a half mirror, and a sub mirror 503, which are moved to a position where they retract from a photographing optical path (mirror-up position) during photographing, and are moved to a position where they enter the photographing optical path (mirror-down position) during finder observation.

When the mirror unit 500 is in the mirror-down position, the main mirror 501 reflects an object light flux having passed through a photographic lens 200 as a component of a photographic optical system of the lens unit 210, thereby guiding the same to the viewfinder optical system 4, and also causes part of the object light flux to transmit therethrough, thereby guiding the same to the sub mirror 503. The sub mirror 503 reflects the object light flux transmitted through the main mirror 501, thereby guiding the same to a focus detection unit 31. Further, when the mirror unit 500 is in the mirror-up position, the object light flux having passed through the photographic lens 200 is guided to an image pickup device 33.

The mirror drive circuit 101 controls driving of a motor 601 (see FIG. 3) for rotating the mirror unit 500 between the mirror-up position (see FIG. 2B) and the mirror-down position (see FIG. 2A), and detects a position of the mirror unit 500.

The focus detection unit 31 is formed by a field lens disposed in the vicinity of an imaging surface, not shown, a reflection mirror, a secondary imaging lens, a diaphragm, a line sensor formed by a plurality of CCD sensors, and so forth. A signal output from the focus detection unit 31 is supplied to the focus detection circuit 102, and is sent to the MPU 100 after being converted to an object image signal. The MPU 100 performs focus detection calculation by a phase difference detection method based on the supplied object image signal. Then, the MPU 100 calculates a defocus amount and a defocus direction, and controls a lens control circuit 201 and an AF drive circuit 202 of the lens unit 210 to drive a focus lens of the photographic lens 200 to an in-focus position based on a result of the calculation.

A pentaprism 22 converts the object light flux reflected by the main mirror 501 in the mirror-down position to an erect normal image to reflect the converted image, whereby a user can view the converted erect normal image, as an object image, from a finder eyepiece window 18 via the viewfinder optical system 4. Further, the pentaprism 22 also guides part of the object light flux to a photometry sensor 23, and the photometric circuit 24 converts photometric results output from the photometry sensor 23 to luminance signals of respective areas on an observation surface, and outputs the luminance signals to the MPU 100. The MPU 100 calculates an exposure value based on the luminance signals output from the photometric circuit 24.

A focal plane shutter 106 blocks an object light flux guided to the image pickup device 33 during finder observation, and during photographing, operates to obtain a desired exposure time based on a time difference between traveling of a front curtain, not shown, and traveling of a rear curtain, not shown, in response to a release signal input by the user. The focal plane shutter 106 is controlled by the shutter drive circuit 103 in response to a command from the MPU 100.

An image pickup device unit 114 is comprised of the image pickup device 33, a laminate-type piezoelectric element 112, and an optical low-pass filter 113. The image pickup device 33 is implemented e.g. by a CCD sensor, a CMOS sensor, or a CID sensor. A clamp/CDS (correlated double sampling) circuit 34 performs basic analog processing before A/D conversion, and is also capable of changing a clamp level. An AGC (automatic gain controller) 35 performs basic analog processing before A/D conversion, and is also capable of changing an AGC basic level. An analog-to-digital converter 36 converts an analog signal output from the image pickup device 33 to a digital signal.

An infrared ray cut filter 32 is formed into a substantially rectangular shape, and cuts unnecessary infrared light of an object light flux to be guided to the image pickup device 33. The infrared ray cut filter 32 has a surface covered by a conductive material in order to prevent foreign matter from sticking thereto. The optical low-pass filter 113 is formed by laminating and affixing a plurality of birefringent plates and phase plates, which are made of quartz, to each other, and further affixing an infrared ray cut filter to the resulting laminate. The laminate-type piezoelectric element 112 is excited by the piezoelectric element drive circuit 111 having received a command from the MPU 100, and vibration thereof is transmitted to the optical low-pass filter 113.

The video signal processing circuit 104 performs general image processing by hardware, such as gamma/knee processing, filtering processing, and information synthesis processing for monitor display, on digital image data. Color image data for monitor display, output from the video signal processing circuit 104 is displayed on a color liquid crystal monitor 19 via a monitor drive circuit 115.

Further, the video signal processing circuit 104 is also capable of storing image data in a buffer memory 37 via a memory controller 38 according to an instruction from the MPU 100. Further, the video signal processing circuit 104 has a function of performing image data compression processing, such as JPEG compression. Further, in a case where images are continuously photographed e.g. by continuous photographing, the video signal processing circuit 104 is also capable of temporarily storing image data in the buffer memory 37, and sequentially reading out unprocessed image data via the memory controller 38. This enables the video signal processing circuit 104 to sequentially perform image processing and compression processing on the unprocessed image data regardless of a rate at which image data is output from the A/D converter 36.

The memory controller 38 has a function of storing image data output from an external interface 40, such as a USB output connector, in a memory 39, and a function of outputting image data stored in the memory 39 to the external interface 40. Note that as the memory 39, for example, a flash memory is used which can be mounted and removed to and from the camera body 1.

A release switch (SW1) 7 a is turned on e.g. by an operation of half-pressing a release button, not shown, and sends an operation signal for starting photographing preparation to the MPU 100 via the switch sensing circuit 105. A release switch (SW2) 7 b is turned on e.g. by an operation of fully pressing the release button, and sends an operation signal for starting photographing to the MPU 100 via the switch sensing circuit 105. Further, the switch sensing circuit 105 sends operation signals to the MPU 100 according to the respective operating states of a main operation dial 8, a sub operation dial 20, a photographing mode-setting dial 14, a main switch 43, and a cleaning instruction member 44.

The display drive circuit 107 drives an external display device 9 and an in-finder display device 41 according to instructions from the MPU 100. The battery check circuit 108 performs battery check for a predetermined time period according to an instruction from the MPU 100, and sends a result of the check to the MPU 100. A power supply section 42 supplies necessary power to the components of the camera according to an instruction provided from the MPU 100 via the power supply circuit 110. The time measurement circuit 109 measures a time period elapsed after the main switch 43 is turned off until the main switch 43 is turned on next, and sends a result of the measurement to the MPU 100 in response to a command from the MPU 100.

Next, a description will be given of the lens unit 210. The lens unit 210 includes the lens control circuit 201, and the lens control circuit 201 performs communication with the MPU 100 of the camera body 1 via the mount contact portion 21. The mount contact portion 21 also has a function of sending a signal to the MPU 100 when the lens unit 210 is connected to the camera body 1.

The lens control circuit 201 performs communication with the MPU 100 by using this function, and drives the photographic lens 200 and the diaphragm, denoted by reference numeral 204, via the AF drive circuit 202 and a diaphragm drive circuit 203. Although FIG. 1 shows one photographic lens 200 for convenience of explanation, the photographic lens 200 is actually formed by a lens group including a plurality of lenses.

The AF drive circuit 202 is comprised of e.g. a stepping motor, and changes the position of the focus lens of the photographic lens 200 in a direction of an optical axis under the control of the lens control circuit 201 to thereby perform the focusing operation. The diaphragm drive circuit 203 is comprised of e.g. an automatic iris, and changes the opening diameter of the diaphragm 204 under the control of the lens control circuit 201 to thereby obtain an optical aperture value.

FIG. 2A is a schematic side cross-sectional view of the camera when the mirror unit 500 is in the mirror-down position. FIG. 2B is a schematic side cross-sectional view of the camera when the mirror unit 500 is in the mirror-up position.

As shown in FIGS. 2A and 2B, the main mirror 501 of the mirror unit 500 is held by a main mirror holder 502, and the sub mirror 503 is held by a sub mirror holder 504. Further, the main mirror holder 502 is rotatably supported with respect to a mirror box 400 (see FIG. 3), and the sub mirror holder 504 is rotatably supported with respect to the main mirror holder 502. The mirror unit 500 is driven by a mirror drive unit 1000, and is turned between the mirror-down position shown in FIG. 2A and the mirror-up position shown in FIG. 2B.

Here, the main mirror 501, the sub mirror 503, the main mirror holder 502, and the sub mirror holder 504 correspond to respective examples of a first mirror, a second mirror, a first mirror holder, and a second mirror holder. Further, the mirror-down position and the mirror-up position of the main mirror holder 502 correspond to respective examples of a first position and a second position. Further, the mirror-down position and the mirror-up position of the sub mirror holder 504 correspond to respective examples of a third position and a fourth position.

In the mirror-down position shown in FIG. 2A, the mirror unit 500 enters the photographing optical path, an object light flux having passed through the photographic lens 200 is reflected by the main mirror 501, and part of the object light flux is transmitted through the main mirror 501 and is reflected by the sub mirror 503. The object light flux reflected by the main mirror 501 is guided to the pentaprism 22 of the viewfinder optical system 4, and the object light flux reflected by the sub mirror 503 is guided to the focus detection unit 31.

Further, in the mirror-up position shown in FIG. 2B, the mirror unit 500 is retracted from the photographing optical path, and an object light flux having passed through the photographic lens 200 is guided to the image pickup device 33 to form an image, which is photoelectrically converted.

FIG. 3 an exploded perspective view of the mirror drive unit 1000. As shown in FIG. 3, the mirror drive unit 1000 includes the mirror box 400, the mirror unit 500, and a mirror charge unit 600.

The main mirror holder 502 of the mirror unit 500 is formed with rotational shafts 502 a, and the rotational shafts 502 a are rotatably supported with respect to the mirror box 400. Further, the main mirror holder 502 is formed with a shaft portion 502 c having a semicircular cross section, and a first contact portion 502 b. When the mirror unit 500 is in the mirror-down position, the shaft portion 502 c of the main mirror holder 502 is urged in a mirror-down direction by the other end of a spring 607 having one end hooked on a spring urging portion 604 d, and the first contact portion 502 b is brought into contact with a positioning shaft 507. The positioning shaft 507 is formed e.g. by an eccentric pin, and by rotating the positioning shaft 507, it is possible to adjust the mirror-down position or the main mirror holder 502. The spring 607 corresponds to an example of an urging member.

The sub mirror holder 504 is formed with support holes 504 a, and is rotatably supported on rotational shaft portions 502 d of the main mirror holder 502 by having the support holes 504 a fitted thereon. This make the sub mirror holder 504 rotatable with respect to the main mirror holder 502 about the rotational shaft portions 502 d.

Further, the sub mirror holder 504 is formed with a drive shaft portion 504 c and a first contact portion 504 b. When the mirror unit 500 is in the mirror-down position, the drive shaft portion 504 c of the sub mirror holder 504 is urged by a spring 608 in the mirror-down direction, and the first contact portion 504 b is brought into contact with a positioning shaft 508. The positioning shaft 508 is formed e.g. by an eccentric pin, and by rotating the positioning shaft 508, it is possible to adjust the mirror-down position of the sub mirror holder 504.

The mirror box 400 is provided with a stopper 505 with which a front end of the main mirror holder 502 rotated to the mirror-up position is brought into contact. The stopper 505 is formed of an elastic member which can absorb impact applied when the main mirror holder 502 is brought into contact with the stopper 505. Further, on a rear side of the mirror box 400, there is disposed a shaft retaining plate 506 for retaining the rotational shafts 502 a of the main mirror holder 502. By attaching the shaft retaining plate 506 to the mirror box 400, the main mirror holder 502 is mounted on the mirror box 400 in a manner rotatable with respect thereto without coming off.

The mirror charge unit 600 is mounted on a right side of the mirror box 400, as viewed from the direction of the optical axis O. The mirror charge unit 600 includes the motor 601, a cam gear 603, a mirror drive lever unit 700, photo-interrupters 609 and 610, and a gear base 611. The motor 601 is supported on the gear base 611, and the gear base 611 is mounted on the right side of the mirror box 400, as viewed from the direction of the optical axis O, with screws 611 s.

FIG. 4 is an exploded perspective view of the mirror charge unit 600. As shown in FIG. 4, the cam gear 603 is rotatably supported on a first shaft portion 611 a of the gear base 611 by having the first shaft portion 611 a fitted in a support hole 603 a thereof, which is the center of rotation. The mirror drive lever unit 700 includes a mirror drive lever 604, a mirror drive gear 605, and a spring 606, and the springs 607 and 608.

The mirror drive lever 604 has a support hole 604 a, which is the center of rotation, and is rotatably supported on a second shaft portion 611 b formed on the gear base 611 by having the second shaft portion 611 b fitted in the support hole 604 a. The mirror drive gear 605 also has a support hole 605 a, which is the center of rotation, and is rotatably supported on the second shaft portion 611 b formed on the gear base 611 by having the second shaft portion 611 b fitted in the support hole 605 a. That is, the mirror drive lever 604 and the mirror drive gear 605 are rotatably mounted with respect to the gear base 611 coaxially with each other.

The mirror drive lever 604 is attached to the mirror drive gear 605 via the spring 606. More specifically, one end 606 a of the spring 606 is hooked on a spring urging portion 604 f which is part of the mirror drive lever 604, and the other end 606 b of the spring 606 is hooked on a spring urging portion 605 g which is part of the mirror drive gear 605.

In this state, the spring 606 is urged in a direction in which the one end 606 a and the other end 606 b thereof sandwich the spring urging portion 604 f and the spring urging portion 605 g. This enables the mirror drive lever 604 to rotate substantially in unison with the mirror drive gear 605. Further, the spring 607 for urging the main mirror holder 502 in the mirror-down direction, and the spring 608 for urging the sub mirror holder 504 in the mirror-down direction are held on the mirror drive lever 604.

The motor 601 formed e.g. by a stepping motor is fixed to the gear base 611, and has a pinion 602 fitted on an output shaft thereof. The mirror drive circuit 101 counts the number of pulses supplied to the motor 601 from the start of driving of the mirror unit 500, and this enables the MPU 100 to recognize the phase of the mirror unit 500 via the mirror drive circuit 101.

When the cam gear 603 and the motor 601 are mounted on the gear base 611, a first gear portion 603 b formed on the cam gear 603 and the pinion 602 of the motor 601 are meshed with each other. Further, when the mirror drive lever unit 700 is mounted on the gear base 611, a second gear portion 603 c formed on the cam gear 603 and a gear portion 605 b of the mirror drive gear 605 are meshed with each other. Therefore, a driving force of the motor 601 is transmitted to the mirror drive lever unit 700 via the cam gear 603. Here, the cam gear 603, the mirror drive lever 604, and the mirror drive gear 605 correspond to an example of a driving member.

The photo-interrupters 609 and 610 are fixedly engaged with a first locking portion 611 c and a second locking portion 611 d, formed on the gear base 611, respectively. As the cam gear 603 is rotated, the states of the photo-interrupters 609 and 610 are each changed by a light shielding plate 603 f formed on the cam gear 603 between a light-receiving state and a non-light-receiving state. The MPU 100 determines the phase of the mirror unit 500 via the mirror drive circuit 101 based on the output signals from the photo-interrupters 609 and 610.

FIG. 5A is a front view of the mirror drive unit 1000 as viewed from the optical axis direction, and FIG. 5B is a right side view of the mirror drive unit 1000. As shown in FIG. 5B, the mirror charge unit 600 is mounted on one of the sides of the mirror box 400.

FIG. 6 is a view of the mirror drive unit 1000 shown in FIG. 5B, with the motor 601 and the gear base 611 removed therefrom. In the state shown in FIG. 6, the mirror unit 500 is in the mirror-down position.

FIG. 7 is a view useful in explaining the relationship between the mirror unit 500 and the mirror charge unit 600. Note that FIG. 7 shows only the mirror unit 500, the mirror drive lever 604, and the springs 607 and 608, appearing in FIG. 6.

Referring to FIG. 7, the center of the rotational shaft 502 a of the main mirror holder 502 is set as A. Further, the center of the support hole 504 a which is the center of rotation of the sub mirror holder 504 in the mirror-down state is set as B, and the center of the support hole 504 a which is the center of rotation of the sub mirror holder 504 in the mirror-up state is set as C. Here, the center A of the rotational shaft 502 a of the main mirror holder 502 corresponds to an example of a first rotation center, and the centers B and C of rotation of the sub mirror holder 504 correspond to an example of a second rotation center.

At this time, as shown in FIG. 7, the center of the support hole 604 a which is the center of rotation of the mirror drive lever 604 is positioned radially inside a segment of a sector formed by connecting B and C with A in the center. This makes it possible to reduce changes in distance from the center of the support hole 604 a which is the center of rotation of the mirror drive lever 604 to the drive shaft portion 504 c of the sub mirror holder 504 during driving of the mirror unit 500. Therefore, it is possible to reduce load variation occurring during driving of the mirror unit 500.

Further, in the present embodiment, the center of the support hole 604 a which is the center of rotation of the mirror drive lever 604 is positioned radially inside the segment of the sector formed about A by connecting B and C, and also in an area closer to B than to C. With this, although detailed description will be given hereinafter, a down lever portion 604 g (see FIG. 8E) of the mirror drive lever 604 passes a route different from a rotation locus of the shaft portion 502 c of the main mirror holder 502 during the mirror-up operation of the mirror unit 500.

Further, when the mirror-down operation of the mirror unit 500 is started, the down lever portion 604 g of the mirror drive lever 604 is brought into contact with the shaft portion 502 c of the main mirror holder 502, and is enabled to assist the mirror-down operation. Note that even when the center of the support hole 604 a which is the center of rotation of the mirror drive lever 604 is positioned radially outside the above-mentioned segment of the sector, the mirror-up/mirror-down operation can be performed. The down lever portion 604 g corresponds to an example of an abutment portion.

Next, a description will be given of mirror-up driving and mirror-down driving of the mirror unit 500, performed by the mirror drive unit 1000, with reference to FIGS. 8A to 8E. FIGS. 8A to 8E are views useful in explaining states of components of the mirror drive unit 1000 when the mirror unit 500 is in the mirror-down position.

FIG. 8A is a front view useful in explaining the states of the components of the mirror drive unit 1000 when the mirror unit 500 is in the mirror-down position. Note that in FIG. 8A, the mirror box 400, the motor 601, and the gear base 611 are omitted. FIG. 8B is a right side view of FIG. 8A. FIG. 8B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610, when the mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8B, the photo-interrupter 609 is in the light-receiving state, and the photo-interrupter 610 is in the non-light-receiving state due to being shielded from light by the light shielding plate 6031 of the cam gear 603. At this time, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 is in the mirror-down state.

FIG. 8C is a cross-sectional view taken along c-c in FIG. 8A. FIG. 8C shows the relationship between the second gear portion 603 c (in FIG. 8C, the reference numeral 603 c denotes an area surrounding the corresponding gear portion as a rectangle indicated by broken lines) of the cam gear 603 and the gear portion 605 b (in FIG. 8C, the reference numeral 605 b denotes an area surrounding the corresponding gear portion as a rectangle indicated by broken lines; the same applies hereafter) of the mirror drive gear 605, when the mirror unit 500 is in the mirror-down position. In the state shown in FIG. 8C, the second gear portion 603 c of the can; gear 603 and the gear portion 605 h of the mirror drive gear 605 are not in mesh with each other.

FIG. 8D is a cross-sectional view taken along d-d in FIG. 8A. FIG. 8D shows the relationship between a first cam portion 603 d and a second cam portion 603 e of the cam gear 603, and a first follower portion 605 c and a second follower portion 605 d of the mirror drive gear 605, when the mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8D, the first cam portion 603 d of the cam gear 603 is in contact with the first follower portion 605 c of the mirror drive gear 605. The first can portion 603 d of the cam gear 603 has a circular arc cam shape concentric with part of the cam gear 603 without a cam lift. Therefore, even when the cam gear 603 is rotated to some degree in a cam area of the first cam portion 603 d in this state, rotation is not transmitted to the mirror drive gear 605, so that the mirror drive gear 605 is not rotated.

Further, in this state, when the mirror drive gear 605 is brought into contact with the cam gear 603, in a state urged in the mirror-up direction (clockwise direction as viewed in FIG. 8D), the mirror drive gear 605 is brought into contact with the cam gear 603 such that the urging force acts in a direction substantially toward the center of rotation of the cam gear 603. Therefore, in the state shown in FIG. 8D, unless the cam gear 603 is rotated, the mirror drive gear 605 restricted from rotating in the mirror-up direction.

FIG. 8E is a cross-sectional view taken along e-e in FIG. 8A. FIG. 8E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), when the mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8E, the spring 607 urges the shaft portion 502 c of the main mirror holder 502 in the mirror-down direction, whereby the first contact portion 502 b of the main mirror holder 502 is brought into contact with the positioning shaft 507. Further, the spring 608 urges the drive shaft portion 504 c of the sub mirror holder 504 in the mirror-down direction, whereby the first contact portion 504 b of the sub mirror holder 504 is brought into contact with the positioning shaft 508.

In this state, an inner peripheral surface of a rectangular hole 604 c of the mirror drive lever 604 is not in contact with the drive shaft portion 504 c of the sub mirror holder 504. With this, only the urging force of the spring 608 acts on the sub mirror holder 504, and hence the mirror unit 500 is stably positioned in the mirror-down position.

The mirror drive lever unit 700 is urged in the mirror-up direction by the reaction forces of the springs 607 and 608. As a result, the first follower portion 605 c of the mirror drive gear 605 is brought into contact with the first cam portion 603 d of the cam gear 603. Then, when the motor 601 is rotated in the mirror-up direction (counterclockwise direction as viewed from the pinion 602) in the state shown in FIGS. 8A to 8E, mirror-up driving of the mirror drive unit 1000 is started, and the state shown in FIGS. 8A to 8E shifts to a state shown in FIGS. 9A to 9E.

FIGS. 9A to 9E are views useful in explaining states of the components of the mirror drive unit 100 immediately before the cam gear 603 and the mirror drive gear 605 are brought into mesh with each other immediately after the mirror drive unit 1000 starts mirror-up driving.

FIG. 9A is a front view showing a state immediately before the mirror unit 500 starts the mirror-up operation, which corresponds to FIG. 8A. FIG. 8B is a right side view of FIG. 9A. FIG. 9B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 immediately after the mirror drive unit 1000 has started mirror-up driving.

As shown in FIG. 9B, the cam gear 603 is rotated in a counterclockwise direction as viewed in FIG. 9B from the state shown in FIGS. 8A to 8E. In this state, the state of the photo-interrupter 609 is changed from the light-receiving state, shown in FIGS. 8A to 8E, to the non-light-receiving state, by the light shielding plate 603 f of the cam gear 603. Further, the photo-interrupter 610 is shielded from light by the light shielding plate 603 f of the cam gear 603, thereby continuing to be in the non-light-receiving state. When the state of the photo-interrupter 609 is changed from the light-receiving state to the non-light-receiving state, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 9C is a cross-sectional view taken along c-c in FIG. 9A. FIG. 9C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 immediately after the mirror drive unit 1000 has started the mirror-up driving.

In the state shown in FIG. 9C, a first gear tooth 603 g of the cam gear 603 enters inside the gear outer circle of the gear portion 605 b of the mirror drive gear 605. At this time, as described above, the first follower portion 605 c is brought into contact with the first cam portion 603 d of the cam gear 603, whereby the mirror drive gear 605 is restricted from rotating in the mirror-up direction. Therefore, a first gear tooth 605 e of the mirror drive gear 605 is positioned outside the gear outer circle of the second gear portion 603 c of the cam gear 603. This enables the second gear portion 603 c of the can; gear 603 and the gear portion 605 b of the mirror drive gear 605 to stably shift to a meshed state.

FIG. 9D is a cross-sectional view taken along d-d in FIG. 9A. FIG. 9D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, immediately after the mirror drive unit 1000 has started mirror-up driving. In the state shown in FIG. 9D, the first follower portion 605 c of the mirror drive gear 605 is in contact with the first cam portion 603 d of the cam gear 603. Further, the second cam portion 603 e of the cam gear 603 and the second follower portion 605 d of the mirror drive gear 605 are not in contact with each other.

FIG. 9E is a cross-sectional view taken along e-e in FIG. 9A. FIG. 9E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately after the mirror drive unit 1000 has started mirror-up driving.

In the state shown in FIG. 9E, the spring 607 urges the shaft portion 502 c of the main mirror holder 502, whereby the first contact portion 502 b of the main mirror holder 502 is brought into contact with the positioning shaft 507. Further, the spring 608 urges the drive shaft portion 504 c of the sub mirror holder 504, whereby the first contact portion 504 b of the sub mirror holder 504 are brought into contact with the positioning shaft 508. When mirror-up driving by the mirror drive unit 1000 progresses from the state shown in FIGS. 9A to 9E, the state shown in FIGS. 9A to 9E shifts to a state shown in FIGS. 10A to 10E.

FIGS. 10A to 10E are views useful in explaining states of the components of the mirror drive unit 1000 immediately before the mirror unit 500 starts a mirror-up operation. FIG. 10A is a front view showing a state immediately before the mirror unit 500 starts the mirror-up operation, which corresponds to FIG. 8A. FIG. 10B is a right side view of FIG. 10A. FIG. 10B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 600 and 610, immediately before the mirror unit 500 starts the mirror-up operation.

As shown in FIG. 10B, the cam gear 603 is further rotated in the counterclockwise direction as viewed in FIG. 10B from the state shown in FIGS. 9A to 9E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, thereby continuing to be in the non-light-receiving state. At this time, as described above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 10C a cross-sectional view taken along c-c in FIG. 10A. FIG. 10C shows the relationship between the first cam portion 603 d of the cam gear 603 and the first follower portion 605 c of the mirror drive gear 605 immediately before the mirror unit 500 starts the mirror-up operation.

In the state shown in FIG. 10C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are meshed with each other. With this, when the cam gear 603 is rotated in the mirror-up direction (counterclockwise direction as viewed in FIG. 10C, the mirror drive lever unit 700 is also rotated in the mirror-up direction (clockwise direction as viewed in FIG. 10C).

Further, at this time, the gear portion 605 b of the mirror drive gear 605 starts to be meshed with the second gear portion 603 c, from the first gear tooth 603 g of the cam gear 603. The first gear tooth 603 g of the cam gear 603 is larger in width in the circumferential direction than the other teeth of the second gear portion 603 c. This improves the gear strength of the second gear portion 603 c of the cam gear 603.

FIG. 10D is a cross-sectional view taken along d-d in FIG. 10A. FIG. 10D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605 immediately before the mirror unit 500 starts the mirror-up operation.

In the state shown in FIG. 10D, the contact state between the first cam portion 603 d of the cam gear 603 and the first follower portion 605 c of the mirror drive gear 605 is released. That is, the mirror unit 500 is released from the locked state in the mirror-down position.

FIG. 10E is a cross-sectional view taken along e-e in FIG. 10A. FIG. 10E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately before the mirror unit 500 starts the mirror-up operation.

In the state shown in FIG. 10E, the spring 607 urges the shaft portion 502 c of the main mirror holder 502, whereby the first contact portion 502 b of the main mirror holder 502 is brought into contact with the positioning shaft 507.

Here, a region in which when the main mirror holder 502 is in a state in the mirror-down position, the sub mirror holder 504 is moved in the mirror-up direction to a position where the sub mirror holder 504 is overlaid on the main mirror holder 502 (region from FIGS. 8A to 8E to FIGS. 12A to 12E) is referred to as a first region. Further, a region in which the main mirror holder 502 and the sub mirror holder 504 are moved to the mirror-up position in a state overlaid upon each other (region from FIGS. 12A to 12E to FIGS. 14A to 14E) is referred to as a second region.

In the state shown in FIG. 10E when in the first region, the spring 608 urges the drive shaft portion 504 c of the sub mirror holder 504, whereby the first contact portion 504 b of the sub mirror holder 504 is brought into contact with the positioning shaft 508. When mirror-up driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 10A to 10E, the state shown in FIGS. 10A to 10E shifts to a state shown in FIGS. 11A to 11G.

FIGS. 11A to 11E are views useful in explaining states of the components of the mirror drive unit 1000 when the sub mirror holder 504 is performing its mirror-up operation. FIG. 11A is a front view showing a state in which the sub mirror holder 504 is performing its mirror-up operation, which corresponds to FIG. 8A. FIG. 11B is a right side view of FIG. 11A. FIG. 11B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 when the sub mirror holder 504 is performing its mirror-up operation.

As shown in FIG. 11B, the cam gear 603 is further rotated in the counterclockwise direction from the state shown in FIGS. 10A to 10E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, thereby continuing to be in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 11C is a cross-sectional view taken along c-c in FIG. 11A. FIG. 11C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 when the sub mirror holder 504 is performing its mirror-up operation.

In the state shown in FIG. 11C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are meshed with each other. Therefore, the driving force of the motor 601 is transmitted to the mirror drive lever unit 700 via the cam gear 603, whereby the mirror drive lever unit 700 is rotated in the mirror-up direction (clockwise direction as viewed in FIG. 11C) from the state shown in FIGS. 10A to 10E.

FIG. 11D is a cross-sectional view taken along d-d in FIG. 11A. FIG. 11D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, when the sub mirror holder 504 is performing its mirror-up operation.

In the state shown in FIG. 11D, the first cam portion 603 d of the cam gear 603 and the first follower portion 605 c of the mirror drive gear 605 are not in contact with each other. Further, the second cam portion 603 e of the cam gear 603 and the second follower portion 605 d of the mirror drive gear 605 are not in contact with each other, either.

FIG. 11F is a cross-sectional view taken along e-e in FIG. 11A. FIG. 11E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), when the sub mirror holder 504 is performing its mirror-up operation.

In the state shown in FIG. 11E, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is brought into contact with the drive shaft portion 504 c of the sub mirror holder 504, whereby the sub mirror holder 504 is rotated in a direction in which the sub mirror holder 504 is closed to the main mirror holder 502 (mirror-up direction). Further, the spring 608 urges the drive shaft portion 504 c of the sub mirror holder 504. The shaft portion 502 c of the main mirror holder 502 continues to be in the state urged by the spring 607, and hence the main mirror holder 502 continues to be in the mirror-down state. When mirror-up driving of the mirror drive unit 1000 progresses from the state shown in FIG. 11A to 11E, the state shown in FIG. 11A to 11E shifts to a state shown in FIGS. 12A to 12E.

FIGS. 12A to 12E are views useful in explaining states of the components of the mirror drive unit 1000 when the main mirror holder 502 starts its mirror-up operation. FIG. 12A is a front view showing a state at the moment when the main mirror holder 502 starts its mirror-up operation, which corresponds to FIG. 8A. FIG. 12B is a right side view of FIG. 12A. FIG. 12B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 when the main mirror holder 502 starts its mirror-up operation.

As shown in FIG. 12B, the cam gear 603 is further rotated in the counterclockwise direction from the state shown in FIGS. 11A to 11E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, continuing to be in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 12C is a cross-sectional view taken along c-c in FIG. 12A. FIG. 12C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 at the moment when the main mirror holder 502 starts its mirror-up operation.

In the state shown in FIG. 12C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are in mesh with each other. Therefore, the driving force of the motor 601 is transmitted to the mirror drive lever unit 700 via the cam gear 603, whereby the mirror drive lever unit 700 is further rotated in the mirror-up direction (clockwise direction as viewed in FIG. 12C) from the state shown in FIGS. 11A to 11E.

FIG. 12D is a cross-sectional view taken along d-d in FIG. 12A. FIG. 12D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605 at the moment when the main mirror holder 502 starts its mirror-up operation.

In the state shown in FIG. 12D, the first cam portion 603 d of the cam gear 603 and the first follower portion 605 c of the mirror drive gear 605 are not in contact with each other. Further, the second cam portion 603 e of the cam gear 603 and the second follower portion 605 d of the mirror drive gear 605 are not in contact with each other, either.

FIG. 12E is a cross-sectional view taken along e-e in FIG. 12A. FIG. 12E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), at the moment when the main mirror holder 502 starts its mirror-up operation.

In the state shown in FIG. 12E, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is in contact with the drive shaft portion 504 c of the sub mirror holder 504, whereby the sub mirror holder 504 is rotated in the direction in which the sub mirror holder 504 is closed to the main mirror holder 502 (mirror-up direction), to be placed in a state overlaid on the main mirror holder 502.

The spring 607 is pressed and urged by a spring urging portion 604 e of the mirror drive lever 604. In this state, the shaft portion 502 c of the main mirror holder 502 is not in contact with the spring 607, and is not urged by the spring 607. This makes it possible to reduce the load applied when the main mirror holder 502 is rotated in the mirror-up direction.

Further, a second contact portion 502 e of the main mirror holder 502 is in contact with a second contact portion 504 d of the sub mirror holder 504. The main mirror holder 502 is rotated in the mirror-up direction by being pushed up by the sub mirror holder 504. At this time, the down lever portion 604 g of the mirror drive lever 604 passes outside the rotation locus of the shaft portion 502 c of the main mirror holder 502. When mirror-up driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 12A to 12E, the state shown in FIGS. 12A to 12E shifts to a state shown in FIGS. 13A to 13E.

FIGS. 13A to 13E are views useful in explaining states of the components of the mirror drive unit 1000 immediately before the mirror unit 500 completes the mirror-up operation. FIG. 13A is a front view showing a state immediately before the mirror unit 500 completes the mirror-up operation, which corresponds to FIG. 8A. FIG. 13B is a right side view of FIG. 13A. FIG. 13B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 immediately before the mirror unit 500 completes the mirror-up operation.

As shown in FIG. 13B, the cam gear 603 is further rotated in the counterclockwise direction from the state shown in FIGS. 12A to 12E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, continuing to be in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 13C is a cross-sectional view taken along c-c in FIG. 13A. FIG. 13C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 immediately before the mirror unit 500 completes the mirror-up operation. In the state shown in FIG. 13C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are released from the meshed state, to enter a non-meshed state.

FIG. 13D is a cross-sectional view taken along d-d in FIG. 13A. FIG. 13D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, immediately before the mirror unit 500 completes the mirror-up operation.

In the state shown in FIG. 13D, the second cam portion 603 e of the cam gear 603 is in contact with the second follower portion 605 d of the mirror drive gear 605, and the cam gear 603 is rotated in the counterclockwise direction to thereby push up the mirror drive gear 605 in the mirror-up direction. This causes the mirror drive lever unit 700 to rotate in the mirror-up direction. Further, the first cam portion 603 d of the cam gear 603 is not in contact with the first follower portion 605 c of the mirror drive gear 605.

FIG. 13E is a cross-sectional view taken along e-e in FIG. 13A. FIG. 13E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately before the mirror unit 500 completes the mirror-up operation.

In the state shown in FIG. 13E, the drive shaft portion 504 c of the sub mirror holder 504 is in contact with the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604, and the sub mirror holder 504 performs the mirror-up operation. Further, the second contact portion 502 e of the main mirror holder 502 in contact with the second contact portion 504 d of the sub mirror holder 504, whereby the main mirror holder 502 performs the mirror-up operation by being pushed up by the sub mirror holder 504.

At this time, the down lever portion 604 g of the mirror drive lever 604 enters the rotation locus of the shaft, portion 502 c of the main mirror holder 502. In a case where the main mirror holder 502 is moved away from the sub mirror holder 504, the shaft portion 502 c of the main mirror holder 502 is brought into contact with the down lever portion 604 g of the mirror drive lever 604. When mirror-up driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 13A to 13E, the state shown in FIGS. 13A to 13E shifts to a state shown in FIGS. 14A to 14E.

FIGS. 14A to 14E are views useful in explaining states of the components of the mirror drive unit 1000 when the mirror unit is in the mirror-up position. FIG. 14A is a front view showing a state when the mirror unit 500 is in the mirror-up position, which corresponds to FIG. 8A. FIG. 14B is a right side view of FIG. 14A. FIG. 14B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 when the mirror unit 500 is in the mirror-up position.

In the state shown in FIG. 14B, the cam gear 603 is further rotated in the counterclockwise direction from the state shown in FIGS. 13A to 13E. In this state, the photo-interrupter 609 is shielded from light by the light shielding plate 603 f of the cam gear 603, continuing to be in the non-light-receiving state, and the photo-interrupter 610 is released from the state shielded from light by the light shielding plate 603 f of the cam gear 603 to enter the light-receiving state.

At this time, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has completed the mirror-up operation, and terminates mirror-up driving of the mirror drive unit 1000.

FIG. 14C is a cross-sectional view taken along c-c in FIG. 14A. FIG. 14C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 when the mirror unit 500 is in the mirror-up position. In the state shown in FIG. 14C, the second gear portion 603 c of the cam gear 603 is not in mesh with the gear portion 605 b of the mirror drive gear 605.

FIG. 14D is a cross-sectional view taken along d-d in FIG. 14A. FIG. 14D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, when the mirror unit 500 is in the mirror-up position.

In the state shown in FIG. 14D, the second follower portion 605 d of the mirror drive gear 605 is in contact, in the urged state, with the second cam portion 603 e of the cam gear 603. The second cam portion 603 e of the cam gear 603 has a circular arc cam shape concentric with the part of the cam gear 603 without a cam lift, as mentioned above. Therefore, even when the cam gear 603 is rotated to some degree in the cam area of the first cam portion 603 d in this state, rotation is not transmitted to the mirror drive gear 605, so that the mirror drive gear 605 is not rotated.

Further, in this state, when the mirror drive gear 605 is brought into contact with the cam gear 603 in a state urged in the mirror-down direction, the mirror drive gear 605 is brought, into contact with the cam gear 603 such that the urging force acts in a direction substantially toward the center of rotation of the cam gear 603. Therefore, in this state, unless the cam gear 603 is rotated, the mirror drive gear 605 is restricted from rotating in the mirror-down direction. This causes the mirror unit 500 to be locked in the mirror-up position.

FIG. 14E is a cross-sectional view taken along e-e in FIG. 14A. FIG. 14E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), when the mirror unit 500 is in the mirror-up position.

In the state shown in FIG. 14E, the drive shaft portion 504 c of the sub mirror holder 504 is in contact with the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604, and the second contact portion 502 e of the main mirror holder 502 is in contact with the second contact portion 504 d of the sub mirror holder 504.

The main mirror holder 502 is in contact with the stopper 505 in a state in which the front end portion thereof elastically deforms the stopper 505. This causes the main mirror holder 502 to receive the urging force in the mirror-down direction, and the second follower portion 605 d of the mirror drive gear 605 is in contact with the second cam portion 603 e of the cam gear 603.

Further, in this state, the mirror drive lever 604 receives the urging force in the mirror-up direction, and the mirror unit 500 is also pushed in the mirror-up direction. At this time, the down lever portion 604 g of the mirror drive lever 604 is not in contact with the shaft portion 502 c of the main mirror holder 502, and is on standby within the rotation locus of the shaft portion 502 c of the main mirror holder 502. When the motor 601 rotates in the mirror-down direction (clockwise direction as viewed from the pinion 602) in the state shown in FIGS. 14A to 14E, and the mirror drive unit 1000 starts mirror-down driving, the state shown in FIGS. 14A to 14E shifts to a state shown in FIGS. 15A to 15E.

FIGS. 15A to 15E are views useful in explaining states of the components of the mirror drive unit 1000 immediately after the mirror drive unit 1000 starts mirror-down driving. FIGS. 15A to 15E show a state immediately after driving of the motor 601 has been started to move the main mirror holder 502 and the sub mirror holder 504 from the mirror-up position toward the mirror-down position.

FIG. 15A is a front view showing a state immediately after the mirror drive unit 1000 has started mirror-down driving, which corresponds to FIG. 8A. FIG. 15B is a right side view of FIG. 15A. FIG. 15B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 immediately after the mirror drive unit 1000 has started mirror-down driving.

In the state shown in FIG. 15B, the cam gear 603 is rotated in the mirror-down direction (clockwise direction as viewed in FIG. 15B), and the photo-interrupter 610 is shielded from light by the light shielding plate 603 f of the cam gear 603, so that the state of the photo-interrupter 610 is changed from the light-receiving state to the non-light-receiving state. The photo-interrupter 609 is shielded from light by the light shielding plate 603 f of the cam gear 603, continuing to be in the non-light-receiving state.

When the state of the photo-interrupter 610 is changed from the light-receiving state to the non-light-receiving state, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 15C is a cross-sectional view taken along c-c in FIG. 15A. FIG. 15C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 immediately after the mirror drive unit 1000 has started mirror-down driving.

In the state shown in FIG. 15C, a second gear tooth 603 h of the cam gear 603 enters inside the gear outer circle of the gear portion 605 b of the mirror drive gear 605. At this time, as described hereinafter with reference to FIG. 15D, the second follower portion 605 d of the mirror drive gear 605 is in contact with the second cam portion 603 e of the cam gear 603, whereby the mirror drive gear 605 is restricted from rotating in the mirror-down direction. Therefore, a second gear tooth 605 f of the mirror drive gear 605 is positioned outside the gear outer circle of the second gear portion 603 c of the cam gear 603. This enables the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 to stably shift to a meshed state.

FIG. 15D is a cross-sectional view taken along d-d in FIG. 15A. FIG. 15D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, immediately after the mirror drive unit 1000 has started mirror-down driving. In the state shown in FIG. 15D, the second cam portion 603 e of the cam gear 603 is in contact with the second follower portion 605 d of the mirror drive gear 605.

FIG. 15E is a cross-sectional view taken along e-e in FIG. 15A. FIG. 15E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately after the mirror drive unit 1000 has started mirror-down driving.

In the state shown in FIG. 15E, the drive shaft portion 504 c of the sub mirror holder 504 is in contact with inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604, and the second contact portion 502 e of the main mirror holder 502 is in contact with the second contact portion 504 d of the sub mirror holder 504.

FIGS. 16A to 16E are views useful in explaining states of the components of the mirror drive unit 1000 immediately before the mirror unit 500 starts the mirror-down operation. FIGS. 16A to 16E show a state immediately after driving of the mirror drive lever 604 has been started to move the main mirror holder 502 and the sub mirror holder 504 from the mirror-up position toward the mirror-down position.

FIG. 16A is a front view showing a state immediately before the mirror unit 500 starts the mirror-down operation, which corresponds to FIG. 8A. FIG. 16B is a right side view of FIG. 16A. FIG. 16B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 immediately before the mirror unit 500 starts the mirror-down operation.

As shown in FIG. 16B, the cam gear 603 is further rotated in the clockwise direction from the state shown in FIGS. 15A to 15E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, and are in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 16C is a cross-sectional view taken along c-c in FIG. 16A. FIG. 16C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 immediately before the mirror unit 500 starts the mirror-down operation.

In the state shown in FIG. 16C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are shifted to the meshed state. With this, when the cam gear 603 is rotated in the mirror-down direction (clockwise direction as viewed in FIG. 16C), the mirror drive lever unit 700 is also rotated in the mirror-down direction (counterclockwise direction as viewed in FIG. 16C).

At this time, the second gear portion 603 c of the cam gear 603 starts to be meshed with the gear portion 605 b of the mirror drive gear 605 from the second gear tooth 605 f of the mirror drive gear 605. The second gear tooth 603 h of the cam gear 603 is larger in width in the circumferential direction than the other teeth of the second gear portion 603 c. This improves the gear strength of the second gear portion 603 c of the cam gear 603.

FIG. 16D is a cross-sectional view taken along d-d in FIG. 16A. FIG. 16D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, immediately before the mirror unit 500 starts the mirror-down operation. In the state shown in FIG. 16D, the contact state between the second cam portion 603 e of the cam gear 603 and the second follower portion 605 d of the mirror drive gear 605 is released.

FIG. 16F is a cross-sectional view taken along e-e in FIG. 16A. FIG. 16E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately before the mirror unit 500 starts the mirror-down operation.

In the state shown in FIG. 16E, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is in contact with the drive shaft portion 504 c of the sub mirror holder 504, and the down lever portion 604 g of the mirror drive lever 604 in contact with the shaft portion 502 c of the main mirror holder 502. With this, when the mirror drive lever 604 is rotated in the mirror-down direction, the sub mirror holder 504 and the main mirror holder 502 can quickly rotate in the mirror-down direction. Therefore, it is possible to reduce the time required for the main mirror 501 to reach the mirror-down position, which makes it possible to reduce time over which an object image is lost during finder observation. When mirror-down driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 16A to 16E, the state shown in FIGS. 16A to 16E shifts to a state shown in FIGS. 17A to 17E.

FIGS. 17A to 17E are views useful in explaining states of the components of the mirror drive unit 1000 when the main mirror holder 502 reaches its mirror-down position. FIG. 17A is a front view showing a state at the moment when the main mirror holder 502 reaches its mirror-down position, which corresponds to FIG. 8A. FIG. 17B is a right side view of FIG. 17A. FIG. 17B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 at the moment when the main mirror holder 502 reaches its mirror-down position.

In the state shown in FIG. 17B, the cam gear 603 further rotated in the clockwise direction from the state shown in FIGS. 16A to 16E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, and are in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 17C is a cross-sectional view taken along c-c in FIG. 17A. FIG. 17C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 at the moment when the main mirror holder 502 reaches its mirror-down position.

In the state shown in FIG. 17C, the second gear portion 603 c of the cam gear 603 is in mesh with the gear portion 605 b of the mirror drive gear 605. Therefore, the driving force of the motor 601 is transmitted to the mirror drive lever unit 700 via the cam gear 603, whereby the mirror drive lever unit 700 is rotated in the mirror-down direction (counterclockwise direction as viewed in FIG. 17C) from the state shown in FIGS. 16A to 16E.

FIG. 17D is a cross-sectional view taken along d-d in FIG. 17A. FIG. 17D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605 at the moment when the main mirror holder 502 reaches its mirror-down position.

In the state shown in FIG. 17D, the second cam portion 603 e of the cam gear 603 and the second follower portion 605 d of the mirror crave gear 605 are not in contact with each other. Further, the first cam portion 603 d of the cam gear 603 and the first follower portion 605 c of the mirror drive gear 605 are not in contact with each other, either.

FIG. 17E is a cross-sectional view taken along e-e in FIG. 17A. FIG. 17F shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), at the moment when the main mirror holder 502 reaches its mirror-down position.

In the state shown in FIG. 17E, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is in contact with the drive shaft portion 501 c of the sub mirror holder 504, whereby the sub mirror holder 504 is rotated in the mirror-down direction. At this time, the down lever portion 604 g of the mirror drive lever 604 passes outside the rotation locus of the shaft portion 502 c of the main mirror holder 502. In this state, the main mirror holder 502 is pulled down by the sub mirror holder 504 to thereby perform the mirror-down operation.

Further, the first contact portion 502 b of the main mirror holder 502 is brought into contact with the positioning shaft 507, and when the main mirror holder 502 bounces after the contact, the main mirror holder 502 is rotated about the rotational shaft 502 a in the mirror-up direction (clockwise direction as viewed in FIG. 17E). At this time, the shaft portion 502 c of the main mirror holder 502 is brought into contact with the spring 607, to receive the urging force in the mirror-down direction. This is suppresses the bounce of the main mirror holder 502.

As mentioned above, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is in contact with the drive shaft portion 504 c of the sub mirror holder 504, whereby the sub mirror holder 504 continues the mirror-down operation. When mirror-down driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 17A to 17E, the state shown in FIGS. 17A to 17E shifts to a state shown in FIGS. 18A to 18E.

FIGS. 18A to 18E are views useful in explaining states of the components of the mirror drive unit 1000 immediately before the sub mirror holder 504 reaches its mirror-down position. FIG. 18A is a front view showing a state immediately before the sub mirror holder 504 reaches its mirror-down position, which corresponds to FIG. 8A. FIG. 18E is a right side view of FIG. 18A. FIG. 18B shows the relationship between the light shielding plate 603 f of the cam gear 603 and the photo-interrupters 609 and 610 immediately before the sub mirror holder 504 reaches its mirror-down position.

In the state shown in FIG. 18B, the cam gear 603 is further rotated in the clockwise direction as viewed in FIG. 18B from the state shown in FIGS. 17A to 17E. In this state, the photo-interrupters 609 and 610 are both shielded from light by the light shielding plate 603 f of the cam gear 603, and are in the non-light-receiving state. At this time, as mentioned above, the MPU 100 determines via the mirror drive circuit 101 that the mirror unit 500 has not completed the mirror-down operation or the mirror-up operation.

FIG. 18C is a cross-sectional view taken along c-c in FIG. 18A. FIG. 18C shows the relationship between the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 immediately before the sub mirror holder 504 reaches its mirror-down position. In the state shown in FIG. 18C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are released from the meshed state, to enter a non-meshed state.

FIG. 18D is a cross-sectional view taken along d-d in FIG. 18A. FIG. 18D shows the relationship between the first cam portion 603 d and the second cam portion 603 e of the cam gear 603, and the first follower portion 605 c and the second follower portion 605 d of the mirror drive gear 605, immediately before the sub mirror holder 504 reaches its mirror-down position.

In the state shown in FIG. 18D, the first cam portion 603 d of the cam gear 603 is brought into contact with the first follower portion 605 c of the mirror drive gear 605, and pushes down the mirror drive gear 605 in the mirror-down direction (counterclockwise direction as viewed in FIG. 18D). This causes the mirror drive lever unit 700 to be rotated in the mirror-down direction. Further, the second cam portion 603 e of the cam gear 603 is not in contact with the second follower portion 605 d of the mirror drive gear 605.

FIG. 18E is a cross-sectional view taken along e-e in FIG. 18A. FIG. 18E shows the relationship between the main mirror holder 502 and the sub mirror holder 504, and the mirror drive lever unit 700 (the mirror drive lever 604, the mirror drive gear 605, and the springs 607 and 608), immediately before the sub mirror holder 504 reaches its mirror-down position.

In the state shown in FIG. 18E, the spring 607 urges the shaft portion 502 c of the main mirror holder 502, whereby the first contact portion 502 b of the main mirror holder 502 is in contact with the positioning shaft 507. Further, the inner peripheral surface of the rectangular hole 604 c of the mirror drive lever 604 is in contact with the drive shaft portion 504 c of the sub mirror holder 504, whereby the sub mirror holder 504 continues the mirror-down operation. When mirror-down driving of the mirror drive unit 1000 progresses from the state shown in FIGS. 18A to 18E, the state shown in FIGS. 18A to 18E shifts to the mirror-down state shown in FIGS. 8A to 8E.

In FIGS. 8A to 8E, as described above, the mirror unit 500 is in the mirror-down position. In this state, as shown in FIG. 8B, the photo-interrupter 609 is released from the state shielded from light by the light shielding plate 603 f of the cam gear 603, to enter the light-receiving state, and the photo-interrupter 610 is shielded from light by the light shielding plate 603 f of the cam gear 603, continuing to be in the non-light-receiving state. At this time, the MPU 100 determines via the mirror drive circuit that the mirror unit 500 has completed the mirror-up operation or the mirror-down operation, and terminates the mirror driving. In the state shown in FIG. 8C, the second gear portion 603 c of the cam gear 603 and the gear portion 605 b of the mirror drive gear 605 are not in mesh with each other.

Further, in the state shown in FIG. 8D, the first cam portion 603 d of the cam gear 603 is in contact with the first follower portion 605 c of the mirror drive gear 605. The first cam portion 603 d of the cam gear 603 has a circular arc cam shape concentric with the part of the cam gear 603 without a cam lift. Therefore, even when the cam gear 603 is rotated to some degree in the cam area of the first cam portion 603 d in this state, rotation is not transmitted to the mirror drive gear 605, so that the mirror drive gear 605 is not rotated.

Further, in this state, when the mirror drive gear 605 in contact with the cam gear 603 receives a urging force in the mirror-up direction, the urging force acts in the direction substantially toward the center of rotation of the cam gear 603. Therefore, in the state shown in FIG. 8D, unless the cam gear 603 is rotated, the mirror drive gear 605 is restricted from rotating in the mirror-up direction. This causes the mirror unit 500 to be locked in the mirror-down position.

Further, the first contact portion 504 b of the sub mirror holder 504 is brought into contact with the positioning shaft 508, and when the sub mirror holder 504 bounces, the sub mirror holder 504 is rotated about the support hole 504 a in the mirror-up direction (counterclockwise direction as viewed in FIG. 8D). At this time, the drive shaft portion 504 c of the sub mirror holder 504 charges the spring 608, and the bounce of the sub mirror holder 504 is suppressed. This makes it possible to reduce the driving sound of the mirror unit 500.

As described above, in the present embodiment, the driving force from the motor 601 is transmitted to the sub mirror holder 504 to thereby rotate the mirror unit 500 between the mirror-down position and the mirror-up position. This eliminates the need of a toggle spring or a reversing cam for driving the sub mirror holder 504. Further, the amounts of charging of the spring 607 and the spring 608 for urging the main mirror holder 502 and the sub mirror holder 504, respectively, can be reduced. This makes it possible to provide a mirror drive device that is capable of achieving lower torque and higher speed in driving of the mirror unit 500, and also improving durability thereof.

FIG. 19A is a graph showing the relationship between the position of the mirror unit 500 and time in the mirror-up operation, and FIG. 19B is a graph showing the relationship between the position of the mirror unit 500 and time in the mirror-down operation. The mirror-up operation in FIG. 19A corresponds to the operation described with reference to FIGS. 8A to 8E to FIGS. 14A to 14E, and the mirror-down operation in FIG. 19B corresponds to the operation described with reference to FIGS. 15A to 15E to FIGS. 18A to 18E and FIGS. 8A to 8E.

Next, a description will be given of control of driving of the mirror unit 500 with reference to FIGS. 20A and 20B. FIG. 20A is a flowchart of a mirror drive control process performed during the mirror-up operation of the mirror unit 500, and FIG. 20B is a flowchart of a mirror drive control process performed during the mirror-down operation of the mirror unit 500. The processes in FIGS. 20A and 20B are performed e.g. by the MPU 100 that loads the programs stored in a storage section, such as the EEPROM 100 a, into a RAM, not shown.

First, the mirror drive control process in the mirror-up operation of the mirror unit 500 will be described with reference to FIG. 20A. In a step S200, when the release button is fully pressed in the mirror-down state shown in FIGS. 8A to 8E, causing the release switch (SW2) 7 b to be turned on, the MPU 100 controls the mirror drive circuit 101 to cause the motor 601 to rotate in the mirror-up direction, and proceeds to a step S201. With this, the sub mirror holder 504 starts to rotate in the mirror-up direction.

In the step S201, when the rotation of the motor 601 causes the state of the photo-interrupter 609 to be changed from the light-receiving state to the non-light-receiving state, the MPU 100 proceeds to a step S202. In the step S202, the MPU 100 controls the mirror drive circuit 101 to start counting of pulses from the motor 601, and proceeds to a step S203.

In the step S203, as shown in FIG. 20A, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value A, the MPU 100 proceeds to a step S204. Here, the time at which the count value reaches A is a time at which the sub mirror holder 504 is rotated to a phase in which the sub mirror holder 504 is in a position closer to its mirror-down position than when the sub mirror holder 504 is in the position in contact with the main mirror holder 502, shown in FIGS. 12A to 12E.

Here, the rotational position of the sub mirror holder 504 at which the pulse count value reaches A corresponds to a predetermined first setting position in the mirror-up operation. In the present embodiment, the rotational position of the sub mirror holder 504 at which the pulse count value reaches A is set to a position closer to the position where the sub mirror holder 504 is brought into contact with the main mirror holder 502 than to a substantially midpoint position of a range through which the sub mirror holder 504 is moved from the mirror-down position to the position where the sub mirror holder 504 is brought into contact with the main mirror holder 502 (see FIG. 19A).

In the step S204, the MPU 100 controls the mirror drive circuit 101 to reduce the speed of the motor 601 to thereby reduce the rotational speed of the sub mirror holder 504, and proceeds to a step S205. With this, as shown in FIGS. 12A to 12E, and 19A, the sub mirror holder 504 which is reduced in speed is brought into contact with the main mirror holder 502.

In the step S205, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value B, the MPU 100 proceeds to a step S206. Here, the time at which the pulse count value reaches B is substantially the same time at which the sub mirror holder 504 is brought into contact with the main mirror holder 502.

In the step S206, when it is detected in the step S205 that the sub mirror holder 504 is brought into contact with the main mirror holder 502, the MPG 100 controls the mirror drive circuit 101 to accelerate the motor 601 in the mirror-up direction, and proceeds to a step S207. With this, the main mirror holder 502 starts its mirror-up operation at high speed in a state in which the sub mirror holder 504 is overlaid thereon in contact therewith, as shown in FIG. 19A.

In the step S207, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value C, the MPU 100 proceeds to a step S208. Here, the time at which the pulse count value reaches C is a time at which the mirror unit 500 is rotated to a phase in which the mirror unit 500 is in a position closer to the mirror-down position than when the mirror unit 500 is in a position reaching the mirror-up position (shown in FIGS. 14A to 14E).

Here, the rotational position of the mirror unit 500 at which the pulse count value reaches C corresponds to a predetermined second setting position in the mirror-up operation. In the present embodiment, the rotational position of the mirror unit 500 at which the pulse count value reaches C is set to a position closer to the mirror-up position than a midpoint position of a range through which the main mirror holder 502 is moved from the mirror-down position to the mirror-up position (see FIG. 19A).

In the step S208, the MPU 100 controls the mirror drive circuit 101 to reduce the speed of the motor 601, and proceeds to a step S209. With this, as shown in FIG. 19A, the sub mirror holder 504 and the main mirror holder 502 are reduced in speed again before the mirror unit 500 reaches the mirror-up position (shown in FIGS. 14A to 14E).

In the step S209, when the state of the photo-interrupter 610 is changed from the non-light-receiving state to the light-receiving state, the MPU 100 proceeds to a step S210. In the step S210, the MPU 100 determines that the mirror unit 500 has reached the mirror-up position shown in FIG. 14A to 14E, and controls the mirror drive circuit 101 to stop driving of the motor 601, followed by terminating mirror-up driving.

Next, the mirror drive control process in the mirror-down operation of the mirror unit 500 will be described with reference to FIG. 20B. In a step S220, the MPU 100 controls the mirror drive circuit 101 to cause the motor 601 to rotate in the mirror-down direction at the mirror-up position of the mirror unit 500, shown in FIGS. 15A to 15E, and proceeds to a step S221. With this, the mirror unit 500 starts the mirror-down operation.

In the step S221, when the mirror drive circuit 101 causes the motor 601 to rotate in the mirror-down direction, causing the state of the photo-interrupter 610 to be changed from the light-receiving state to the non-light-receiving state, the MPU 100 proceeds to a step S222. In the step S222, the MPU 100 controls the mirror drive circuit 101 to start counting of pulses from the motor 601, and proceeds to a step S223.

In the step S223, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value D, the MPU 100 proceeds to a step S224. Here, the time at which the pulse count value reaches D is a time at which the main mirror holder 502 is rotated to a phase in which the main mirror holder 502 is in a position closer to the mirror-up position than when the main mirror holder 502 is in the position reaching the mirror-down position, shown in FIGS. 17A to 17E.

Here, the rotational position of the mirror unit 500 at which the pulse count value reaches D corresponds to a predetermined first setting position in the mirror-down operation. In the present embodiment, the rotational position of the mirror unit 500 at which the pulse count value reaches D is set to a position closer to the mirror-down position than to a midpoint position of a range through which the main mirror holder 502 is moved from the mirror-up position to the mirror-down position (see FIG. 19B).

In the step S224, the MPU 100 controls the mirror drive circuit 101 to reduce the speed of the motor 601 to thereby reduce the rotational speed of the mirror unit 500, and proceeds to a step S225. With this, as shown in FIGS. 17A to 17E, and B, the main mirror holder 502 reaches the mirror-down position at a reduced speed.

In the step S225, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value E, the MPU 100 proceeds to a step S226. Here, the time at which the count value reaches F is substantially the same time at which the main mirror holder 502 reaches the mirror-down position, shown in FIGS. 17A to 17E.

In the step S226, when it is detected that the main mirror holder 502 has reached the mirror-down position, shown in FIGS. 17A to 17E, the MPU 100 controls the mirror drive circuit 101 to accelerate the motor 601 in the mirror-down direction, and proceeds to a step S227. With this, the sub mirror holder 504 is accelerated and rotated in the mirror-down direction again when the main mirror holder 502 has reached the mirror-down position.

In the step S227, when the count value of the pulses from the motor 601, which is counted by the mirror drive circuit 101, reaches a predetermined value F, the MPU 100 proceeds to a step S228. Here, the time at which the pulse count value reaches F is a time at which the sub mirror holder 504 is rotated to a phase in which the sub mirror holder 504 is in a position closer to its mirror-up position than when the sub mirror holder 504 is in a position reaching the mirror-down position, shown in FIGS. 8A to 8E.

Here, the rotational position of the sub mirror holder 504 at which the pulse count value reaches F corresponds to a predetermined second setting position in the mirror-down operation. In the present embodiment, the rotational position of the mirror unit 500 at which the pulse count value reaches F is set to a position closer to the mirror-down position of the sub mirror holder 504 than to a substantially midpoint position of a range through which the sub mirror holder 504 is moved from the position where the main mirror holder 502 reaches its mirror-down position to the mirror-down position of the sub mirror holder 504.

In the step S228, the MPU 100 controls the mirror drive circuit 101 to reduce the speed of the motor 601, and proceeds to a step S229. With this, the sub mirror holder 504 is rotated in the mirror-down direction at a reduced speed, and reaches the mirror-down position.

In the step S229, when the state of the photo-interrupter 609 is changed from the non-light-receiving state to the light-receiving state, the MPU 100 proceeds to a step S230. In the step S230, the MPU 100 determines that the mirror unit 500 has reached the mirror-down position, and controls the mirror drive circuit 101 to stop driving of the motor 601, followed by terminating mirror-down driving.

As described above, in the present embodiment, in the mirror-up operation, it is possible to reduce the impact caused when the sub mirror holder 504 and the main mirror holder 502 are brought into contact with each other, and the impact caused when the mirror unit 500 reaches the mirror-up position. Therefore, it is possible to suppress the mirror bounce, and reduce the mirror driving sound in the mirror-up operation of the mirror unit 500.

Further, in the present embodiment, in the mirror-down operation, it is possible to reduce the impact caused when the main mirror holder 502 and the sub mirror holder 504 are brought into contact with the positioning shaft 507 and the positioning shaft 508 at the respective mirror-down positions. This makes it possible to suppress the mirror bounce, and reduce the mirror driving sound in the mirror-down operation of the mirror unit 500.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Applications No. 2015-242910 filed Dec. 14, 2015 and No. 2015-242911, filed Dec. 14, 2015, which are hereby incorporated by reference herein in their entirety. 

What is claimed is:
 1. A mirror drive device comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, the second mirror reflects and object light flux through the first mirror; a motor; and a driving member configured to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position, wherein said driving member directly contacts with said second mirror holder and moves said second mirror holder from the third position to the fourth position, whereby said first mirror holder is moved from the first position to the second position.
 2. The mirror drive device according to claim 1, wherein when said second mirror holder is moved from the third position to the fourth position by said driving member, the mirror drive device has a first region in which said second mirror holder is moved without the first mirror holder being moved, and a second region in which said first mirror holder and said second mirror holder are both moved.
 3. The mirror drive device according to claim 2, further comprising an urging member configured to urge said first mirror holder toward the first position, and wherein in the second region, said urging member does not urge said first mirror holder toward the first position.
 4. The mirror drive device according to claim 2, wherein in the second region, said first mirror holder and said second mirror holder are moved in a state overlaid upon each other.
 5. The mirror drive device according to claim 1, wherein said driving member includes a contact portion that is brought into contact with said first mirror holder, and wherein said contact portion is brought into contact with said first mirror holder, after said motor drives said driving member such that said second mirror holder is moved toward the third position from a state in which said first mirror holder is positioned in the second position and said second mirror holder is positioned in the fourth position.
 6. The mirror drive device according to claim 5, wherein when said driving member moves said second mirror holder from the fourth position to the third position, said contact portion is brought into contact with said first mirror holder to thereby move said first mirror holder from the second position to the first position.
 7. The mirror drive device according to claim 5, wherein when said first mirror holder is moved from the second position to the first position, said contact portion enters a state in which said contact portion is not in contact with said first mirror holder before said first mirror holder reaches the first position.
 8. The mirror drive device according to claim 1, wherein said first mirror holder is attached to a mirror box in a manner rotatable about a first rotation center, wherein said second mirror holder is attached to said first mirror holder in a manner rotatable about a second rotation center which is different from the first rotation center, wherein said driving member is attached to the mirror box in a manner rotatable about a rotation center which is different from the first rotation center and the second rotation center, and wherein the rotation center of said driving member is disposed radially inside radially inside a segment of a sector formed about the first rotation center by connecting the second rotation center located when said second mirror holder is in the third position and the second rotation center located when said second mirror holder is in the fourth position.
 9. The mirror drive device according to claim 8, wherein the rotation center of said driving member is disposed in an area closer to the second rotation center located when said second mirror holder is in the third position than to the second rotation center located when said second mirror holder is in the fourth position.
 10. A mirror drive device comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path; a motor; a driving member configured to directly contact with said second mirror holder and to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position; and a control unit configured to control driving of said motor, wherein when said second mirror holder is moved from the third position to the fourth position by said driving member, said first mirror holder is positioned in the first position without being moved until said second mirror holder is brought into contact therewith, and after said second mirror holder is brought into contact therewith, said first mirror holder is moved to the second position together with said second mirror holder, and wherein said control unit controls said motor to reduce speed thereof to thereby reduce speed of said second mirror holder when said second mirror holder reaches a predetermined first setting position before said second mirror holder is brought into contact with said first mirror holder, controls said motor to increase the speed thereof to thereby increase the speed of said second mirror holder after said second mirror holder is brought into contact with said first mirror holder, and controls said motor to reduce the speed thereof to thereby reduce the speed of said second mirror holder when said first mirror holder is moved toward the second position together with said second mirror holder and reaches a predetermined second setting position before reaching the second position.
 11. The mirror drive device according to claim 10, wherein the predetermined first setting position is a position closer to a position where said second mirror holder is brought into contact with said first mirror holder than to a substantially midpoint position of a range through which said second mirror holder is moved from the third position to the position where said second mirror holder is brought into contact with said first mirror holder.
 12. The mirror drive device according to claim 10, wherein the predetermined second setting position is a position closer to the second position than to a midpoint position of a range through which said first mirror holder is moved from the first position to the second position.
 13. A mirror drive device comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path; a motor; a driving member configured to directly contact with said second mirror holder and to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position; and a control unit configured to control driving of said motor, wherein when said second mirror holder is moved from the fourth position to the third position by said driving member, said first mirror holder is moved from the second position toward the first position together with said second mirror holder, and reaches the first position, and after said first mirror holder reaches the first position, said second mirror holder is moved toward the third position, and reaches the third position, and wherein said control unit controls said motor to reduce speed thereof to thereby reduce the speed of said second mirror holder, when said first mirror holder is moved from the second position toward the first position together with said second mirror holder and reaches a predetermined first setting position before reaching the first position, controls said motor to increase the speed thereof to thereby increase the speed of said second mirror holder after said first mirror holder reaches the first position, and controls said motor to reduce the speed thereof to thereby reduce the speed of said second mirror holder when said second mirror holder reaches a predetermined second setting position before reaching the third position.
 14. The mirror drive device according to claim 13, wherein the predetermined first setting position is a position closer to the first position than to a midpoint position of a range through which said first mirror holder is moved from the second position to the first position.
 15. The mirror drive device according to claim 13, wherein the predetermined second setting position is a position closer to the third position than to a substantially midpoint position of a range through which said second mirror holder is moved from a position where said second mirror holder reaches the first position of said first mirror holder together with said first mirror holder to the third position.
 16. An image pickup apparatus comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path, the second mirror reflects and object light flux through the first mirror; a motor; and a driving member configured to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position, wherein said driving member directly contacts with said second mirror holder and moves said second mirror holder from the third position to the fourth position, whereby said first mirror holder is moved from the first position to the second position.
 17. An image pickup apparatus comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path; a motor; a driving member configured to directly contact with said second mirror holder and to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position; and a control unit configured to control driving of said motor, wherein when said second mirror holder is moved from the third position to the fourth position by said driving member, said first mirror holder is positioned in the first position without being moved until said second mirror holder is brought into contact therewith, and after said second mirror holder is brought into contact therewith, said first mirror holder is moved to the second position together with said second mirror holder, and wherein said control unit controls said motor to reduce speed thereof to thereby reduce speed of said second mirror holder when said second mirror holder reaches a predetermined first setting position before said second mirror holder is brought into contact with said first mirror holder, controls said motor to increase the speed thereof to thereby increase the speed of said second mirror holder after said second mirror holder is brought into contact with said first mirror holder, and controls said motor to reduce the speed thereof to thereby reduce the speed of said second mirror holder when said first mirror holder is moved toward the second position together with said second mirror holder and reaches a predetermined second setting position before reaching the second position.
 18. An image pickup apparatus comprising: a first mirror holder that holds a first mirror and is configured to be movable between a first position in a photographing optical path and a second position retracted from the photographing optical path; a second mirror holder that holds a second mirror in a state rotatably attached to said first mirror holder and is configured to be movable between a third position in the photographing optical path and a fourth position retracted from the photographing optical path; a motor; a driving member configured to directly contact with said second mirror holder and to be driven by said motor to thereby move said second mirror holder between the third position and the fourth position; and a control unit configured to control driving of said motor, wherein when said second mirror holder is moved from the fourth position to the third position by said driving member, said first mirror holder is moved from the second position toward the first position together with said second mirror holder, and reaches the first position, and after said first mirror holder reaches the first position, said second mirror holder is moved toward the third position, and reaches the third position, and wherein said control unit controls said motor to reduce speed thereof to thereby reduce the speed of said second mirror holder, when said first mirror holder is moved from the second position toward the first position together with said second mirror holder and reaches a predetermined first setting position before reaching the first position, controls said motor to increase the speed thereof to thereby increase the speed of said second mirror holder after said first mirror holder reaches the first position, and controls said motor to reduce the speed thereof to thereby reduce the speed of said second mirror holder when said second mirror holder reaches a predetermined second setting position before reaching the third position. 